Electric hand tool

ABSTRACT

An electric hand tool includes a housing, which houses a driving mechanism and a chuck for driving a bit, a battery pack for providing electricity to the driving mechanism, and a switch unit installed in the housing. The switch unit has a switch, an operating member for switching on/off the switch to control supply of electricity from the battery pack to the driving mechanism, and a switching lever extended out of a through hole in the rear portion of the housing and forming a switching portion for operation by the thumb of the hand holding the housing to drive the switching lever to change the direction of electric current and to further reverse the direction of rotation of the driving mechanism.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electric hand tool and more particularly, to such an electric hand tool, which is practical for use in a narrow place for enabling the user to conveniently change the direction of rotation of the electric hand tool.

2. Description of the Related Art

A commercially available electric hand tool essentially comprises a housing, a driving mechanism installed in the housing, a chuck coupled to the driving mechanism and partially extended out of the housing to hold a bit, a battery pack for providing electricity to the driving mechanism, and a switch unit. The switch unit comprises an ON/OFF switching button for operation by the user to determine whether the electricity provided by the battery pack is supplied to the driving mechanism, and a direction switching member for operation by the user to determine the direction of electric current provided by the battery pack and to further determine the rotation direction of the driving mechanism that drivers the chuck.

The conventional direction switching member has a switching rod having an end coupled to a switch that controls the direction of the supplied electric current, and the other end connected to an operation member. The operation member has two ends extended respectively out of two opposite lateral sidewalls of the housing of the electric hand tool for operation by the user such that the switch is controlled to determine the direction of electric current provided by the battery pack by the operation member through the switching rod.

This design of electric hand tool is functional; however, it is not convenient for use in a narrow place. When wishing to reverse the direction of rotation of the electric hand tool during working of the electric hand tool in a narrow place that has no room for the user's hand to operate the operation member, the user shall have to stop the operation, and remove the electric hand tool out of the narrow place, and then to adjust the operation member to change the direction of electric current provided by the battery pack, and then to insert the electric hand tool into the narrow place again. This inconvenient operation situation lowers the working efficiency. In addition, the conventional electric hand tool has no indication to tell the direction of rotation thereof. The user must press the ON/OFF switching button to power the electric hand tool so as to learn the direction of rotation thereof whenever the electric hand tool is not operated. This is inconvenient.

SUMMARY OF THE INVENTION

It is the primary objective of the present invention to provide an electric hand tool, which is practical for use in a narrow place for enabling the user to conveniently change the direction of rotation of the electric hand tool.

To achieve this objective of the present invention, the electric hand tool comprises a housing, a driving mechanism installed in the housing, a chuck, a battery pack for providing electricity to the driving mechanism, and a switch unit installed in the housing. The housing has a front portion provided with an opening, and a rear portion. The chuck is coupled to the driving mechanism and extends out of the opening of the housing to hold a bit for turning by the driving mechanism. The switch unit has a switch, an operating member connected to the switch for switching on/off the switch to control supply of electricity from the battery pack to the driving mechanism, and a switching lever for driving the switch to change the direction of electric current provided by the battery pack. The switching lever has a switching portion at one end thereof. The rear portion of the housing has a through hole through which the switching portion of the switching lever extends for operation by a user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an electric hand tool according to a first preferred embodiment of the present invention.

FIG. 2 is a partial sectional view of the electric hand tool according to the first preferred embodiment of the present invention.

FIG. 3 is a rear view of the electric hand tool according to the first preferred embodiment of the present invention.

FIG. 4 is a partial sectional view of an electric hand tool according to a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-3, an electric hand tool 10 in accordance with the first preferred embodiment of the present invention is shown comprised of a housing 20, a driving mechanism 30, a chuck 40, a battery pack 50, and a switch unit 60.

The housing 20 comprises a first part 21 and a second part 22. The first part 21 has a first end 23 and a second end 24. The first end 23 has a front portion 25 and an opening 26 in the front portion 25. The second part 22 extends from the second end 24 of the first part 21 at an angle. The second part 22 has a rear portion 27 opposite to the front portion 25 of the first end 23 of the first part 21, and a through hole 28 in the rear portion 27. The second part 22 further has an opening 29.

The driving mechanism 30 is installed in the first part 21 of the housing 20, comprising a motor 31.

The chuck 40 is installed in the first part 21 of the housing 20 and coupled to the driving mechanism 30, having a chuck shell 41 extending out of the opening 26 of the housing 20 to hold a bit (not shown) for working.

The battery pack 50 is detachably fastened to the rear end of the second part 22 of the housing 20 to provide electricity to the motor 31 of the driving mechanism 30.

The switch unit 60 is installed in the second part 22 of the housing 20, comprising an operating rod 61, a switching lever 62, and a switch 63. The operating rod 61 has one end connected to the switch 63 and the other end connected to a button 64 that extends out of the housing 20 through the opening 29. The user can press the button 64 to control the switch 63. The switching lever 62 is comprised of a first link 65 and a second link 66. The first link 65 is pivoted to the top of the switch 63, and forwardly backwardly turnable relative to switch 63 to control the switch 63 to change the direction of electric current provided by the battery pack 50. The second link 66 has one end pivoted to the free end 67 of the first link 65 and the other end extended out of the through hole 28 in the rear portion 27 of the housing 20 and forming a switching portion 68 for pushing by the user. The user can push the switching portion 68 to force the second link 66 to pivot the first link 65, thereby causing the switch 63 to change the direction of electric current provided by the battery pack 50. In addition, the switching portion 68 has an indication zone 69 on which letters of “R” (not shown) and “L” are marked for indicating the right-handed and left-handed rotation direction. As shown in FIG. 3, when the switching portion is pushed to left end of the through hole 28, the indication letter of “L” can be seen by the user such that the user can learns that the hand tool is under a left-handed rotation status.

When using the electric hand tool 10, the user can hold the second part 22 of the housing 20 with the hand and press the button 64 with the forefinger to drive the operating rod 61 and to further switch on the switch 65, thereby causing the battery pack 50 to provide electricity to the motor 31. Further, the user can move the switching portion 68 of the switching lever 62 with the thumb, causing the second link 66 to bias the first link 65 and to further drive the switch 63 to change the direction of electric current provided by the battery pack 50, and therefore the direction of rotation of the bit of the electric hand tool 10 is revered.

As indicated above, the switching portion 68 for controlling the direction of rotation of the bit of the electric hand tool 10 is set in the rear portion 27 of the housing 20. Therefore, the user can conveniently drive the switching portion 68 with the thumb to change the direction of electric current when using the electric hand tool 10 in a narrow work place. Further, the indication zone 69 of the switching portion 68 provides directly the direction of rotation of the hand tool to the user, thereby enhancing the working convenience.

The switching lever is not limited to the aforesaid design. FIG. 4 shows a second preferred embodiment of the present invention. According to this embodiment, the electric hand tool 70 is comprised of a housing 71, a driving mechanism 72, a battery pack 73, and a switch unit 74. The housing 71, the driving mechanism 72, and the battery pack 73 are similar to the corresponding members of the aforesaid first embodiment. The switch unit 74 comprises a switching lever 75 and a switch 76. The switching lever 75 has one end pivoted to the switch 76, and the other end extended out of a through hole 78 of the housing 71 and forming a switching portion 77. The user can directly drive the switching portion 77 to switch the switch 76, causing the switch 76 to change the direction of electric current provided by the battery pack 50. 

1. An electric hand tool comprising: a housing having a front portion provided with an opening, and a rear portion; a driving mechanism installed in said housing; a chuck coupled to said driving mechanism and extending out of the opening of said housing to hold a bit for turning by said driving mechanism; a battery pack for providing electricity to said driving mechanism; and a switch unit installed in said housing, said switch unit having a switch, an operating member connected to said switch for switching on/off said switch to control supply of electricity from said battery pack to said driving mechanism, and a switching lever for driving said switch to change the direction of electric current provided by said battery pack, said switching lever having a switching portion at one end thereof; wherein said rear portion of said housing has a through hole through which said switching portion of said switching lever extends for operation by a user; and wherein said switching lever has a first end pivoted to said switch and a second end forming said switching portion.
 2. The electric hand tool as claimed in claim 1, wherein said switching lever comprises a first link having a first end pivoted to said switch and a second end, and a second link having a first end pivoted to the second end of said first link and a second end forming said switching portion.
 3. (canceled)
 4. The electric hand tool as claimed in claim 1, wherein said switching portion has an indication zone for indicating the direction of rotation of the chuck. 